Minimal test case to reproduce: Create two files, async.rb: ``` class Xmms::Collection::Async end ``` collection.c: ``` void Init_Collection() { mXmms = rb_define_module("Xmms"); cColl = rb_define_class_under(mXmms, "Collection", rb_cObject); /* Document-const: Xmms::Collection::NS_ALL * * I am documentation */ rb_define_const(cColl, "NS_ALL", rb_str_new2(XMMS_COLLECTION_NS_ALL)); } ``` Build with: rdoc async.rb collection.c And notice the lack of the NS_ALL constant.